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How did Seleucus I Nicator build the Seleucid Empire?

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Mythological figure — Hellenistic age The figure, who is possibly Dionysus, riding a panther, a Hellenistic opus tessellatum emblema from the House of Masks in Delos, Greece, 2nd century bce.

Seleucus I Nicator built the Seleucid Empire by leveraging his position as a former general of Alexander the Great during the power struggles that followed Alexander's death.12

After serving as the satrap of Babylonia, Seleucus was forced out by Antigonus I Monophthalmus. He spent years in exile, eventually forging a coalition with Ptolemy I, Lysimachus, and Cassander to oppose Antigonus. In 312 BCE, Seleucus successfully reconquered Babylon, an event that marked the beginning of the Seleucid era.12

Following this, he consolidated his power and expanded his domain:
* Eastward Expansion: He extended his reach toward the Indus River, eventually reaching a pact with Chandragupta of the Mauryan Empire that involved territorial concessions in exchange for 500 elephants.12
* Westward Consolidation: He defeated Antigonus at the Battle of Ipsus in 301 BCE, gaining control of Syria and moving his capital to Antioch.12
* Final Acquisitions: In 281 BCE, he defeated Lysimachus at the Battle of Corupedium, bringing him close to reuniting the entirety of Alexander’s former empire before his assassination later that year.12